1. Field of the Invention
The present invention relates to solar heat collectors, and more specifically to covers for such collectors which permit expansion and contraction without having problems with seals.
2. Prior Art
Various solar heat collectors at the present time use types of glazing for covers. A particular prior art cover is shown in United States patent application Ser. No. 843,685, filed Oct. 19, 1977 for Cover For Solar Heat Collector now U.S. Pat. No. 4,224,928. In that cover assembly, the supports are disclosed so that the support ribs that are provided for the cover are gripped in transversely extending fixed supports under the cover and expansion of the cover in longitudinal direction is restrained.
Various types of glazing and mountings have been utilized. For example, double walled covers have been used to float directly in a swimming pool, such as that shown in U.S. Pat. No. 3,072,920. A plastic hollow panel is shown in U.S. Pat. No. 3,886,705. A stressed skin roof for a solar heat collector is illustrated and described in U.S. Pat. No. 4,076,013. The latter two patents show tubular, double wall cover panels.
While the swimming pool cover would appear to be permitted to expand and retract, it would either buckle when expanded or leave space around the edges of the pool when contracted. Usage of the device in relation to a rigid support frame is not disclosed. The rigid covers, which must have some structural strength when supported on a fixed installation, such as the roof of a home or similar places, have not previously provided for good control of the expansion and contraction problems.
U.S. Pat. No. 3,937,208 illustrates a multiple pane cover with flexible sealing strips between the flat panels which also support the panels.